Waterblasting safety cage

Abstract

A safety cage is used in waterblasting with a lance comprising a hollow rod and a nozzle having a diameter larger than the diameter of the rod. The safety cage is an enclosure having an open bottom and a transparent top. The top has a slot and a means for allowing movement through the slot of the rod but not the nozzle of the lance.

1. A method of waterblasting a tube in a tube-and-shell heat exchanger having a plurality of tubes, the ends of which form a flat surface, the method comprising:
 (a) obtaining a lance comprising a hollow rod having a diameter and a nozzle having a diameter greater than the diameter of the rod; 
 (b) obtaining a safety cage comprising an enclosure with an open bottom and a transparent top, the top having a slot and a means for allowing movement through the slot of the rod but not the nozzle of the lance; 
 (c) passing the lance through the slot in the safety cage such that the nozzle is contained within the cage and the rod extends outwardly through the slot; 
 (d) connecting the lance to a source of high pressure water which flow is regulated by a valve; and 
 (e) placing the cage over a tube with the open bottom of the cage resting against flat surface formed by the ends of the tubes, inserting the lance into the tube, opening the valve, and discharging high pressure water into tube. 
 
   
   
     2. The method of  claim 1  wherein slot of the safety cage has a width greater than the diameter of the rod and less than the diameter of the nozzle. 
   
   
     3. The method of  claim 2  wherein the safety cage has a weight of at least about five pounds. 
   
   
     4. The method of  claim 3  wherein the top of the safety cage is perforated. 
   
   
     5. The method of  claim 1  wherein the safety cage additionally comprises a sleeve that slides along the slot, the sleeve having a diameter greater than the rod and less than the nozzle.